Return-Path: linux-nfs-owner@vger.kernel.org Received: from mx12.netapp.com ([216.240.18.77]:10788 "EHLO mx12.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753734AbaDXMqW (ORCPT ); Thu, 24 Apr 2014 08:46:22 -0400 Message-ID: <53590798.80309@netapp.com> Date: Thu, 24 Apr 2014 08:46:16 -0400 From: Anna Schumaker MIME-Version: 1.0 To: NeilBrown CC: Jan Kara , Jeff Layton , Trond Myklebust , Dave Chinner , "J. Bruce Fields" , Mel Gorman , "Andrew Morton" , , , Subject: Re: [PATCH 4/5] SUNRPC: track when a client connection is routed to the local host. References: <20140423022441.4725.89693.stgit@notabene.brown> <20140423024058.4725.7703.stgit@notabene.brown> <5357C3AC.9090203@netapp.com> <20140424091419.0ba0cfd3@notabene.brown> In-Reply-To: <20140424091419.0ba0cfd3@notabene.brown> Content-Type: text/plain; charset="ISO-8859-1" Sender: linux-nfs-owner@vger.kernel.org List-ID: On 04/23/2014 07:14 PM, NeilBrown wrote: > On Wed, 23 Apr 2014 09:44:12 -0400 Anna Schumaker > wrote: > >> On 04/22/2014 10:40 PM, NeilBrown wrote: >>> If requests are being sent to the local host, then NFS will >>> need to take care to avoid deadlocks. >>> >>> So keep track when accepting a connection or sending a UDP request >>> and set a flag in the svc_xprt when the peer connected to is local. >>> >>> The interface rpc_is_foreign() is provided to check is a given client >>> is connected to a foreign server. When it returns zero it is either >>> not connected or connected to a local server and in either case >>> greater care is needed. >>> >>> Signed-off-by: NeilBrown >>> --- >>> include/linux/sunrpc/clnt.h | 1 + >>> include/linux/sunrpc/xprt.h | 1 + >>> net/sunrpc/clnt.c | 25 +++++++++++++++++++++++++ >>> net/sunrpc/xprtsock.c | 17 +++++++++++++++++ >>> 4 files changed, 44 insertions(+) >>> >>> diff --git a/include/linux/sunrpc/clnt.h b/include/linux/sunrpc/clnt.h >>> index 8af2804bab16..5d626cc5ab01 100644 >>> --- a/include/linux/sunrpc/clnt.h >>> +++ b/include/linux/sunrpc/clnt.h >>> @@ -173,6 +173,7 @@ void rpc_force_rebind(struct rpc_clnt *); >>> size_t rpc_peeraddr(struct rpc_clnt *, struct sockaddr *, size_t); >>> const char *rpc_peeraddr2str(struct rpc_clnt *, enum rpc_display_format_t); >>> int rpc_localaddr(struct rpc_clnt *, struct sockaddr *, size_t); >>> +int rpc_is_foreign(struct rpc_clnt *); >>> >>> #endif /* __KERNEL__ */ >>> #endif /* _LINUX_SUNRPC_CLNT_H */ >>> diff --git a/include/linux/sunrpc/xprt.h b/include/linux/sunrpc/xprt.h >>> index 8097b9df6773..318ee37bc358 100644 >>> --- a/include/linux/sunrpc/xprt.h >>> +++ b/include/linux/sunrpc/xprt.h >>> @@ -340,6 +340,7 @@ int xs_swapper(struct rpc_xprt *xprt, int enable); >>> #define XPRT_CONNECTION_ABORT (7) >>> #define XPRT_CONNECTION_CLOSE (8) >>> #define XPRT_CONGESTED (9) >>> +#define XPRT_LOCAL (10) >>> >>> static inline void xprt_set_connected(struct rpc_xprt *xprt) >>> { >>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>> index 0edada973434..454cea69b373 100644 >>> --- a/net/sunrpc/clnt.c >>> +++ b/net/sunrpc/clnt.c >>> @@ -1109,6 +1109,31 @@ const char *rpc_peeraddr2str(struct rpc_clnt *clnt, >>> } >>> EXPORT_SYMBOL_GPL(rpc_peeraddr2str); >>> >>> +/** >>> + * rpc_is_foreign - report is rpc client was recently connected to >>> + * remote host >>> + * @clnt: RPC client structure >>> + * >>> + * If the client is not connected, or connected to the local host >>> + * (any IP address), then return 0. Only return non-zero if the >>> + * most recent state was a connection to a remote host. >>> + * For UDP the client always appears to be connected, and the >>> + * remoteness of the host is of the destination of the last transmission. >>> + */ >>> +int rpc_is_foreign(struct rpc_clnt *clnt) >>> +{ >>> + struct rpc_xprt *xprt; >>> + int conn_foreign; >>> + >>> + rcu_read_lock(); >>> + xprt = rcu_dereference(clnt->cl_xprt); >>> + conn_foreign = (xprt && xprt_connected(xprt) >>> + && !test_bit(XPRT_LOCAL, &xprt->state)); >>> + rcu_read_unlock(); >>> + return conn_foreign; >>> +} >>> +EXPORT_SYMBOL_GPL(rpc_is_foreign); >>> + >>> static const struct sockaddr_in rpc_inaddr_loopback = { >>> .sin_family = AF_INET, >>> .sin_addr.s_addr = htonl(INADDR_ANY), >>> diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c >>> index 0addefca8e77..74796cf37d5b 100644 >>> --- a/net/sunrpc/xprtsock.c >>> +++ b/net/sunrpc/xprtsock.c >>> @@ -642,6 +642,15 @@ static int xs_udp_send_request(struct rpc_task *task) >>> xdr->len - req->rq_bytes_sent, status); >>> >>> if (status >= 0) { >>> + struct dst_entry *dst; >>> + rcu_read_lock(); >>> + dst = rcu_dereference(transport->sock->sk->sk_dst_cache); >>> + if (dst && dst->dev && (dst->dev->features & NETIF_F_LOOPBACK)) >>> + set_bit(XPRT_LOCAL, &xprt->state); >>> + else >>> + clear_bit(XPRT_LOCAL, &xprt->state); >>> + rcu_read_unlock(); >>> + >> You repeat this block of code a bit later. Can you please make it an inline helper function? > > Thanks for the suggestion. > I've put > > static inline int sock_is_loopback(struct sock *sk) > { > struct dst_entry *dst; > int loopback = 0; > rcu_read_lock(); > dst = rcu_dereference(sk->sk_dst_cache); > if (dst && dst->dev && > (dst->dev->features & NETIF_F_LOOPBACK)) > loopback = 1; > rcu_read_unlock(); > return loopback; > } > > > in sunrpc.h, and used it for both the server-side and the client side. Awesome, thanks! Anna > > NeilBrown >